Mining is a complex operation that requires large machines and machine operators to undertake challenging tasks in potentially dangerous environments. Typical mining machines such as continuous miners, feeder breakers, roof bolters, utility vehicles for mining, load haul dump (LHD) vehicles, underground mining loaders and underground articulated trucks are under significant stress during everyday mining operations. For example, mining machines may be subject to rock falls onto the machine or the complete collapse or cave-in of a mine wall or roof onto the machine. In the case where significant amounts rock or other material has fallen onto the machine, retrieval of the machine by towing may be required to remove the machine, and possibly the machine operator, from the work environment. Alternatively, other damage to the machine or other engine difficulties may indefinitely immobilize the machine, therefore requiring tow retrieval of the machine from the environment.
Like all disabled machines, mining machines may require preparation for towing, including disengagement of the brakes. Typically, machines include a hydraulic brake system that is spring loaded and hydraulically disengaged. Specifically, springs maintain the brakes in an engaged mode until the activation of hydraulic pressure overcomes the force of the springs and releases the brakes. In a dead engine situation, or where operation of the engine is not feasible, there is normally no hydraulic pressure available to release the brakes. This is typically desired to prevent the machine from moving when engine failure occurs, or to keep the machine from moving when the engine is turned off. However, if towing the machine is required, it may be necessary to release the brakes. Machines are therefore oftentimes adapted with brake release systems. Certain brake release systems include an independent brake circuit that is activated by the depressing of an activation piston. For example, when depressed, the activation piston charges the brake circuits with hydraulic pressure, releasing the spring applied, fluid release brakes. Thereafter, the machine may then be retrieved or towed out of the work environment. Oftentimes, due to dangerous conditions, remote control applications are utilized to recover machines in areas of unsupported ground. Alternatively, if such remote controlled applications are unavailable, an LHD machine or other mining machine may be employed for the towing of the disabled mining machine.
For retrieval purposes, mining machine frames are sometimes permanently equipped with towing devices or other means that work in combination with brake release systems, which are also permanently fixed to the machine frame. Depending on such factors as the weight and size of the machine, the particular mine and the retrieval vehicle, several mining machine frames are available. For example, a frame having a tow hook welded thereto, or otherwise permanently modified with a tow hook, may be preferred where the retrieval operation will employ a cable delivered to the tow hook via a remotely controlled apparatus. Alternatively, if the retrieval vehicle is a loader, a machine frame configuration that works in combination with a retrieval instrument mounted to the loader may be preferred. In all cases, however, the mining machine frame is permanently modified with the towing attachment or configuration prior to deployment into the mine and, therefore, the towing options are limited. As such, the number of retrieval vehicles exploitable for towing the disabled machine are also limited. Furthermore, any necessary onsite adaption of a mining machine to facilitate towing is impossible. Such limitations are undesirable from both an efficiency standpoint as well as a safety standpoint. This is especially true where a machine operator is trapped within a disabled machine and time is of the essence. Accordingly, it would be beneficial to provide a machine frame and tow retrieval system that allows for the utilization of multiple, interchangeable towing attachments, which are fitted to the machine without modifying the frame structure or having to weld attachments thereon. In this manner, the above-described inefficiencies typically associated with tow retrieval operations of mining machinery may be avoided. Additionally, such a machine frame and tow retrieval system would also provide mining machine owners and operators significant flexibility in terms of tow retrieval options.